Backup and recovery software products are crucial for enterprise level network clients. Customers rely on backup systems to efficiently back up and recover data in the event of user error, data loss, system outages, hardware failure, or other catastrophic events to allow business applications to remain in service or quickly come back up to service after a failure condition or an outage. Data protection and comprehensive backup and disaster recovery (DR) procedures become even more important as enterprise level networks grow and support mission critical applications and data for customers.
The advent of virtualization technology has led to the increased use of virtual machines as data storage targets. Virtual machine (VM) disaster recovery systems using hypervisor platforms, such as vSphere from VMware or Hyper-V from Microsoft, among others, have been developed to provide recovery from multiple disaster scenarios including total site loss. Although disaster recovery procedures provide a reliable method of backing up critical enterprise data, most DR processes take a large amount of time to recover. Even in newer networks that utilize disk-based targets, the time to recover can remain significant, and may not meet the recovery time objectives (RTOs) and recovery point objectives (RPOs) of today's business needs. One main drawback is that during disaster recovery, present methods still require blocks to be copied from the virtual hard disk files (e.g., VHDx) to the host disks.
Providing availability of virtual machine backup files for instant system restore requires newer data restoration techniques. One common approach is to mount the virtual machine directly from the machine/server where the backup file is present. This involves the making the file on the remote machine accessible to the server via standard network-based file sharing protocols like CIFS/NFS (Common Internet File System/Network File System).
This requires additional configurations to be made on the remote machine side, thus adding significantly to administrative overhead. Furthermore, different backup platforms support different file sharing protocols. For example, Unix-based operating systems support NFS, while operating systems such as Microsoft Windows do not support NFS-based network file share protocols, but instead support the CIFS protocol. A popular backup platform, such as EMC Networker supports UNIX as a storage node to interface it from Windows-based systems, and thus require an interface to the NFS protocol, and Networker currently has support to interface with NFS servers via client library. However, resolving different network transfer protocols is a challenge for backup solutions that rely on network share through a specific file transfer protocol. It also requires additional configurations to be made on the remote machine side.
Previous solutions to this issue involved emulating virtual machine backup files present in the remote machine as if it were present on the local machine in a local volume that is formatted with a known file system, such as NTFS using native protocols like DDBoost for Data Domain systems or custom NFS client libraries for Unix storage servers. This approach involves a kernel mode volume redirector driver and a corresponding user mode process that handles the I/O requests from the kernel mode driver objects. Since this involves a kernel component (i.e., a driver to redirect I/O requests), the implementation and maintenance of drivers across multiple platforms and operating system versions is needed. The same solution must thus be reworked for newer or varied versions of each operating system. Furthermore, since this approach was designed for system recover scenarios, and these comprise a smaller number of volumes in a machine, scalability issues emerge with multiple large virtual machines in a Hyper-V system.
FIG. 1 is a diagram that illustrates the use of redirector drivers and corresponding user mode processes, as currently used in present systems. As shown in FIG. 1, a set of volumes 122 denoted volumes 1, 2, 3, . . . N, each have respective virtual volume kernel objects 124 that reside in kernel mode 121. Each kernel mode volume object has a corresponding redirector process 126 that resides in user mode. The user mode redirector processes then communication with the remote host 128. For I/O operations, the user mode processes 126 handle the I/O requests from the kernel mode driver objects 124 for the remote host (e.g., Data Domain host) 128. In a system with a large number of virtual machines (e.g., 50 VMs or more) the implementation and maintenance of the kernel mode volume redirector drivers and corresponding user mode redirector processes imposes a significant time and processing overhead. FIG. 1 may illustrate an example case of a VHD/VHDx system having one partition/volume within the disk, and in which a backup manager includes user mode redirectors that process communications with the DD/remote host, and kernel mode volume redirector drivers that read the data volumes.
Given the drawbacks stated above with respect to present systems, what is needed, therefore, is an instant data recovery/restore method that does not require a network share of the remote virtual machine hard disk files and without changing the original backup files. What is further needed is an instant recovery/restore method that is scalable for different systems and recovery applications.
The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions. EMC, Data Domain, Data Domain Restorer, and Data Domain Boost are trademarks of EMC Corporation.